<p>Merges two users having different <code>IdentityId</code>s, existing in the same identity pool, and identified by the same developer provider. You can use this action to request that discrete users be merged and identified as a single user in the Cognito environment. Cognito associates the given source user (<code>SourceUserIdentifier</code>) with the <code>IdentityId</code> of the <code>DestinationUserIdentifier</code>. Only developer-authenticated users can be merged. If the users to be merged are associated with the same public provider, but as two different users, an exception will be thrown.</p> <p>The number of linked logins is limited to 20. So, the number of linked logins for the source user, <code>SourceUserIdentifier</code>, and the destination user, <code>DestinationUserIdentifier</code>, together should not be larger than 20. Otherwise, an exception will be thrown.</p> <p>You must use AWS Developer credentials to call this API.</p>

{
  "success": true,
  "data": {
    "id": "abc123",
    "created_at": "2025-01-01T00:00:00Z"
  }
}

{
  "success": false,
  "error": {
    "code": "VALIDATION_ERROR",
    "message": "Invalid request parameters"
  }
}